The Canceller uses internal AGC circuitry to compensate for level changes in the downlink path due to rain fades, LNA switchover, etc. The effect of the AGC is to provide a fixed level at the Rx output and hence, a variable gain in the receive path.

2. Virtual Output Power Mode: The “virtual” composite receive output level, within the cancellation bandwidth, is programmable between +10 to -25 dBm for a given valid input level. The “virtual” output level is the level that would correspond to the sum of the powers of the return signals (far signals) plus the forward signal (near signal) if it were not cancelled, in the cancellation bandwidth. However there is an upper limit: assuming the Near/Far PSD ratio is at least +10 dB, the VPCMA-L does not allow actual output power to exceed -5 dBm.

Output P1 dB

≥ +10 dBm

Amplitude response (input to output)

± 1.0 dB over 54 MHz

Phase noise

The integrated phase noise is less than 2.5 degrees RMS when integrating from 10 Hz to 54 MHz

Spurious emissions that originate within the VPCMA-L and which appear at receive input port (Rx In)

25 dB below peak power density of un-cancelled forward carrier across the selected band (up to 54 MHz) from 950 to 2150 MHz (Goal)

Frequency error from Rx In to Rx Out

Not more than 1 Hz of frequency error to the signal provided at the receive output (Rx Out).

Channel Characteristics Specifications

Phase Noise

10 Hz

100 Hz

1 kHz

10 kHz

100 kHz

1 MHz

10 MHz

>10 MHz

-25 dBc/Hz

-25 dBc/Hz

-50 dBc/Hz

-73 dBc/Hz

-93 dBc/Hz

-103 dBc/Hz

-114 dBc/Hz

-114 dBc/Hz

Amplitude response (Offset from center)

± 0.89 * (BWc/2)

± 0.96 * (BWc/2)

± 1.00 * (BWc/2)

Where BWc = Cancellation BW in MHz

p-p variation (dB)

3

4

5

Group Delay (Offset from center)

± 0.22*(BWc/2)

± 0.44*(BWc/2)

± 0.67*(BWc/2)

± 0.89*(BWc/2)

± 1.00*(BWc/2)

Where BWc = Cancellation BW in MHz

p-p variation (ns)

144*(2/BWc)

189*(2/BWc)

369*(2/BWc)

1152*(2/BWc)

2340*(2/BWc)

Frequency error

≤ ± 100 kHz

Frequency rate of change

≤450 Hz per hour. For operation on satellites with inclination up to 1 degree. A satellite with 1 degree inclination produces a Doppler shift (at Ku-band): ± 1750 Hz over 12 hour period.

Channel gain change rate

≤1 dB per second. Includes all sources such as rain fades, uplink stability, downlink stability, etc.

Round trip propagation time

User selectable from 0 to 300 msec.

Adjacent Carrier Interference

The Canceller will suppress the near signal power as specified in the presence of the following adjacent channel environment. 2 adjacent carriers (one on each side) with identical modulation and symbol rates as forward signal (near signal). Carrier spacing of ≥ 1.34 times the symbol rate. Peak carrier power density 6 dB higher than forward carrier. Side lobe spectral re-growth of –26 dBc/4 kHz relative to peak adjacent carrier power density (-20 dBc/4 kHz relative to peak forward carrier power density) for each adjacent carrier. (This could mean –17 dBc/4 kHz for composite of two aggregate carriers relative to forward carrier). The Canceller will not remove adjacent channel energy that may be present in the far channel BW.

Non-linear transponder operation

The Canceller may be operated in the non-linear region (close to saturation) of the satellite transponder.

Cancellation Performance Specifications

Far signal waveform (desired signal to demodulate)

Any

Near signal waveform (signal to be cancelled)

BPSK, QPSK, 8-PSK, 16-APSK

Near signal (forward carrier) bandwidth

1.8 MHz to 48.6 MHz

Cancellation bandwidth

The basic VPCMA-L has a maximum cancellation BW of 2 MHz, with options up to 54MHz. The cancellation BW is the 30 dB BW of the greater of the near signal and the far signal(s). Signal energy outside the specified cancellation BW will not be cancelled or passed through.

Near signal (forward carrier) suppression performance

(Goal) 25 dB

Initial training and acquisition

Less than 1 minute if:

a) The installer enters uplink to downlink round trip delay of forward signal (in msec) with an accuracy of +/- 1 msec, OR

b) The installer enters latitude/longitudes for the VPCMAL and the satellite to 1E-7 degree precision, AND

Cancellation performance in the presence of non-linear satellite channel distortion

The VPCMA-L is a linear canceller and will suppress near signal linear components. Non-linear near signal components will not be suppressed.

Ratio of near signal power to far signal plus noise power

The EHC meets all performance specifications when the PSD ratio Near Signal / ( Far Signal plus Noise ) within the near signal’s 3 dB BW is ≥ -7 dB

Near signal BW to far signal BW ratio

BWc x 0.9 / 4 <= nearFsym <= BWc x 0.9

Where BWc = Cancellation BW in MHz and nearFsym is the near symbol rate. However, there is a lower limit: nearFsym must be at least 512 ksps.

Control, Alarm and Redundancy Specifications

Front panel display and control

Two line LCD display and numerical keypad for data entry.

Front panel status indicators

Power On/Off

Canceller enabled / disabled

Canceller locked

Fault

Test

Remote / (Local)

Rear panel controls

Power On/Off

Remote alarm indicator

Two identical form “C” relay contact closures are available as indicators of an alarm condition. One relay is for the redundancy subsystem and the second is available for remote equipment status.

The relay contacts (NO, NC, COM) are present on two separate DB-9 female connectors located on the rear panel.

The contact rating is at least 1 Ampere at –48 VDC.

Remote Control Interface

10BaseT/100BaseT/1000Base T Ethernet port with SNMP data interface.

Redundancy

A 1:1 redundancy configuration may be used to provide switchover capability. A failure of the primary unit results in an automatic switchover to the backup unit. Additional components are required as listed in 4.1.1.